The discovery of dystrophin and its gene has led to major advances in our understanding of the molecular basis of Duchenne, Becker and other muscular dystrophies related to the dystrophin-associated protein complex. The concept that dystrophin has a mechanical function in stabilizing the muscle fiber membrane has expanded in the last five years. The dystrophin-glycoprotein complex is now considered a multifunctional complex that contains molecules involved in signal transduction cascades important for cell survival. The roles of dystrophin and the dystrophinglycoprotein complex in positioning and anchoring receptors and ion channels is also important, and much of what is known about these functions is based on studies of the neuromuscular synapse. In this review, we discuss the components and the cellular signaling molecules associated with the dystrophin-glycoprotein complex. We then focus on the molecular organization of the neuromuscular junction and its structural organization in the dystrophin-deficient muscle fibers of mdx mice, a well-established experimental model of Duchenne muscular dystrophy.